California gears up for solar eclipse impacts

OREANDA-NEWS. March 26, 2015. The operator of California's primary electricity grid is studying the effects of the 20 March solar eclipse on European power markets to better prepare for predictable natural phenomena that will affect the rapidly growing solar resources in the biggest US state.

The California Independent System Operator, which manages a grid serving three-quarters of the state's population, could add 11GW of utility-scale solar capacity by 2020 in addition 5.4GW on line last year. That total does not include more than 2GW of distributed solar generation, which likewise has expanded at a fast pace.

The most-recent, partial solar eclipse that affected California, on 23 October 2014, removed 1GW of solar generation from the grid, according to a presentation by chief executive Steve Berberich released ahead of tomorrow's meeting of the Independent System Operator board of governors.

The California grid operator expects that 5-7GW of solar generation will be forced off line during the 21 August 2017 total eclipse, which will affect western US between 10am and noon PT. The projected total could amount to more than 20pc of the summer morning load and will require dispatch of replacement capacity, most likely natural gas, or increase imports from the hydropower-rich northwest US.

Last week's eclipse resulted in significant volatility in German intra-day power market as solar generation fell to 6.2GW from 13GW.

"Despite the loss of generation, the [European] grid operators managed through it without disruption and we look forward to any lessons learned they provide," according to Berberich's prepared remarks.

The California grid operator already has to deal with significant and rising real-time volatility because of rising solar generation. Excessive daytime generation hours forces dispatchers to order solar curtailments even though prices can drop to about negative \\$150/MWh. Negative prices in October-December 2014 occurred in more than 5pc of intervals in the five-minute real-time scheduling cycle.

Over-generation and curtailments worry the grid operator especially as state political leaders are considering an increase in the renewable energy procurement mandate to 50pc from the current 33pc.

The grid operator plans to study new transmission infrastructure needs resulting from the proposed increase of the renewable portfolio standard. The grid operator warned last year that the observed curtailment of solar and wind capacity will undermine the state mandate even at 40pc, without mitigating measures.

Solar generation keeps setting new records on the California's primary grid. The latest was 5,812MW on 6 March.